Conventionally, a method using an atomizer with a pin type rotary disk has been known in a spray-drying granulation method, one of the methods for manufacturing particles. For example, Patent Literature 1 discloses a spray part that constitutes an atomizer. The spray part includes a slurry hose discharging a slurry and a pin type rotary disk centrifugally spraying the slurry. The pin type rotary disk herein includes a doughnut-shaped upper board, a planar circular-shaped lower board, and a plurality of dispersing pins arranged in a circumferential direction in an outer circumference of an upper surface of the lower board. The dispersing pins connect the upper board and the lower board. In a spray-drying apparatus disclosed in Patent Literature 1, the slurry discharged from the slurry hose is dropped on the surface of the lower board of the rotating rotary disk. The slurry moves to the outer circumference of the surface of the lower board by centrifugal force due to rotation of the rotary disk and is sprayed from the rotary disk through the dispersing pins. The sprayed slurry is then dried with hot air so as to obtain particles.